Field of the Invention
The present invention relates to a liquid discharge head and a recording apparatus.
Description of the Related Art
In recording apparatuses that discharge liquid such as ink from discharge orifices to record on a recording medium, increasing the number of discharge orifices enables the amount of ink discharged at one time to be increased, thereby enabling high-speed recording. Particularly, full-line recording apparatuses that discharge liquid while continuously conveying a recording medium use a liquid discharge head having long discharge orifice rows of which the length is equal to the transverse width of the recording medium or longer. Such liquid discharge heads use an array of multiple recording element boards that have discharge orifices and discharge elements that generate discharge energy to discharge ink from the discharge orifices.
However, when recording using such liquid discharge heads, there are cases where some recording element boards are used more than others depending on the recording data, and some of the recording element boards may not be used for a long time. In such a case, moisture in the liquid may evaporate near the discharge orifices of the recording element boards that were not used, leading to thickening of the ink, and defective discharge may occur. This defective discharge means cases where ink is not discharged at all, the discharged ink droplet is larger or smaller than the intended size, or the direction in which the ink is discharged is deviated from the intended direction, resulting in the droplet landing position of ink on the recording medium is deviated from the intended position.
A configuration has been proposed to circulate liquid within pressure chambers, to reduce occurrence of such defective discharge. Circulating the liquid keeps liquid from stagnating, so evaporation of moisture from the liquid occurs less readily. Japanese Patent No. 4851310 discloses a recording apparatus having such a configuration to circulate liquid. This recording apparatus has a first common channel and a second common channel that communicate with the discharge orifices formed in the recording element board, and a flow of liquid is generated near the discharge orifices by creating pressure difference within these channels.
However, there has been a possibility with the image forming apparatus described in Japanese Patent No. 4851310 that differential pressure (pressure difference) might occur among the multiple recording element boards, causing variation to occur in the circulatory flows in the pressure chambers. In this case, defective discharge, such different amounts of liquid being discharged at each recording element board, may occur.